This is my first gas forge - still using it most of the time; The refractory is KaoLin formed refractory lining.
I used 3/16" HR Plate to build this HEFTY girl. Don't like moving her around much either.
I made a really simple Ron Reil Style burner with a floor flange bolted on instead of the flared end. There is a slight flare on the inside of the flange and I cut a flared opening in the refractory lining - it works beautifully and can reach forge welding temps between 10 and 15 psi really quickly or around 8psi if I feel like waiting around or working on other stuff first.